improve test readability

Co-authored-by: Kevin Liu <kevinjqliu@users.noreply.github.com>

Author: kevinjqliu

tests/test_transforms.py

@@ -1025,20 +1025,21 @@ def test_projection_truncate_string_starts_with(bound_reference_str: BoundRefere
     ) == StartsWith(term="name", literal=literal("he"))
 
 
-def test_projection_truncate_string_not_starts_with(bound_reference_str: BoundReference) -> None:
-    # literal_width (5) > truncate width (2): no inclusive projection possible (unsafe)
+def test_projection_truncate_string_not_starts_with_longer_literal(bound_reference_str: BoundReference) -> None:
+    # Not a valid projection: return None because pruning on "he" could drop qualifying rows like "help".
     assert TruncateTransform(2).project("name", BoundNotStartsWith(term=bound_reference_str, literal=literal("hello"))) is None
 
 
 def test_projection_truncate_string_not_starts_with_shorter_literal(bound_reference_str: BoundReference) -> None:
-    # literal_width (2) == truncate width (2): project to !=
+def test_projection_truncate_string_not_starts_with_equal_width_literal(bound_reference_str: BoundReference) -> None:
+    # Valid projection: improve NOT STARTS WITH "he" to partition != "he".
     assert TruncateTransform(2).project(
         "name", BoundNotStartsWith(term=bound_reference_str, literal=literal("he"))
     ) == NotEqualTo(term="name", literal=literal("he"))
 
 
-def test_projection_truncate_string_not_starts_with_original_literal(bound_reference_str: BoundReference) -> None:
-    # literal_width (1) < truncate width (2): keep original literal
+def test_projection_truncate_string_not_starts_with_shorter_literal(bound_reference_str: BoundReference) -> None:
+    # Valid projection: pass the NOT STARTS WITH literal "h" through unchanged.
     assert TruncateTransform(2).project(
         "name", BoundNotStartsWith(term=bound_reference_str, literal=literal("h"))
     ) == NotStartsWith(term="name", literal=literal("h"))